This invention is concerned with improvements in or relating to the storing and handling of hollow rivets, especially when loading them onto a mandrel for use in pull-through blind riveting.
In one kind of well known blind-riveting system (that is to say, a fastening system whereby a hollow rivet can be set in aligned holes in superposed parts of a workpiece from one side only of the workpiece) a column of 30 to 60 rivets, say, depending on their length, is assembled with the rivets head-to-tail on a mandrel which, at the tail end of the foremost rivet, has a setting head. The mandrel is inserted in a blind-riveting tool which has means for gripping the mandrel at its rearward end and moving it back and forth, a split nosepiece which can abut the head of the foremost rivet and hold it against the accessible face of the workpiece while the mandrel is pulled through the rivet to set it, and means for urging the rivets forward after each setting stroke so as to project the foremost one through the nosepiece and up to the mandrel head ready for the next riveting operation. This kind of blind-riveting system will be referred to hereinafter as "pull-through blind riveting".
A mandrel for use in pull-through blind riveting has to be of high quality to ensure that it is strong enough not to break while yet it is thin enough to be accommodated in the bores of the rivets, and is therefore an expensive item which it is customary to use over and over again rather than dispense with it after setting one column of rivets. Accordingly, it is necessary to load it with a fresh column of rivets when one column has been used up.
Loading a mandrel with rivets by hand by picking them up one-by-one from a container and making sure they are all loaded the right way round is a slow and laborious procedure which is customarily avoided for example by packaging the rivets, in line head-to-tail, between strips of card or tape, slotted if need be to receive the rivet heads, in such a manner that a mandrel can readily be threaded through the aligned rivet bores and the card or tape thereafter stripped away. Such a procedure is somewhat clumsy and results in an untidy accumulation of waste packaging materials.
It has also been proposed, in United Kingdom Patent Specification 1,029,118, to thread the rivets head-to-tail on a wire rod, bent over at one end to stop the rivets falling off that end and with a friction ring to stop them falling off at the other. The specification describes how such an assemblage could, when required, be laid on one part of a two part jig, each part having a longitudinal channel for the rivet shanks and transverse grooves for their heads so that when the jig parts are closed the rivets are maintained in alignment and the wire rod can be removed and replaced by a rivet-setting mandrel. Such a procedure would avoid the accumulation of litter, but necessitate the availability of jigs for each length and diameter of rivet.